Evaluation of H9N2 Infection Determinants in Qazvin Broiler Farms During 2016-17: A Cohort Study

  Background and Objectives: Avian influenza (AI) is one of the most important respiratory diseases in the poultry industry that causes huge economic impacts and plays an important role in public health. H9N2 Avian Influenza Virus (H9N2 AIV) has a broad circulation and causes endemic infections in the poultry industry of the country.   Methods: A cohort study was conducted from July 2016 to November 2017 in broiler chicken farms of Qazvin Province, Iran to detect H9N2 AIV infection determinants in broiler chicken farms.   Results: Sixteen out of 34 units that were included in the study had positive PCR results. Some variables such as “type of fence around the unit”, “biosecurity”, “cooling system status”, “mean maternal antibody titers”, “location height”, “proximity to public traffic lanes” and “number of units within a radius of 1 km” had significant effects on the infection occurrence in poultry units according to univariate statistical analyses (P<0.05). However, only two of them (“biosecurity” and “cooling system status”) were statistically significant in multi-variable analyses (P<0.05).   Conclusion: Biosecurity measures should be implemented more seriously and strictly in broiler farms to reduce the impact of H9N2 AIV infection.